Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
using namespace std;

int h, w;

int main () {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> h >> w;
  char s[h][w];
  int b = 0;
  int d[h][w];
  int dx[] = {1, 0, -1, 0};
  int dy[] = {0, 1, 0, -1};
  rep(i, h) {
    rep(j, w) {
      cin >> s[i][j];
      if (s[i][j] == '#') ++b;
      d[i][j] = 0;
    }
  }
  d[0][0] = 1;
  queue<pair<int, int> > q;
  q.emplace(0, 0);
  while (!q.empty()) {
    int y = q.front().first;
    int x = q.front().second;
    q.pop();
    for (int i = 0; i < 4; ++i) {
      int yy = y + dy[i];
      int xx = x + dx[i];
      if (0 <= xx && 0 <= yy && xx < w && yy < h && s[yy][xx] == '.' && d[yy][xx] == 0) {
        d[yy][xx] = d[y][x] + 1;
        q.emplace(yy, xx);
      }
    }
  }
  if (d[h-1][w-1] == 0) cout << -1;
  else cout << (h*w - b - d[h-1][w-1]);
}